Math Problem Statement

In the diagram, AFGB is a straight line, BCEF is a parallelogram and triangle EFG is an isosceles triangle. Find (i) angle GFE (ii) angle FEA

In the diagram, AFGB is a straight line, BCEF is a parallelogram and triangle EFG is an isosceles triangle. Find (i) angle GFE (ii) angle FEA

Solution

Let's solve the given problem step by step based on the information in the diagram:

Given:

  1. AFGBAFGB is a straight line.
  2. BCEFBCEF is a parallelogram.
  3. Triangle EFGEFG is an isosceles triangle with EF=EGEF = EG.
  4. EAF=40\angle EAF = 40^\circ and CEF=65\angle CEF = 65^\circ.

(i) To find GFE\angle GFE:

  • Since EFGEFG is an isosceles triangle with EF=EGEF = EG, the base angles GFE\angle GFE and FEG\angle FEG are equal.
  • The sum of the angles in a triangle is 180180^\circ, so: GFE+FEG+EFG=180\angle GFE + \angle FEG + \angle EFG = 180^\circ
  • Given that EFG=65\angle EFG = 65^\circ, we can set GFE=FEG=x\angle GFE = \angle FEG = x. x+x+65=180x + x + 65^\circ = 180^\circ 2x=1152x = 115^\circ x=57.5x = 57.5^\circ Therefore, GFE=57.5\angle GFE = 57.5^\circ.

(ii) To find FEA\angle FEA:

  • Since AFGBAFGB is a straight line, the angles along this line add up to 180180^\circ. Therefore: FEA+EAF=180\angle FEA + \angle EAF = 180^\circ FEA+40=180\angle FEA + 40^\circ = 180^\circ FEA=140\angle FEA = 140^\circ

Answers:

  1. GFE=57.5\angle GFE = 57.5^\circ
  2. FEA=140\angle FEA = 140^\circ

Would you like more details on this, or do you have any questions?

Here are 5 related questions to consider:

  1. What is the measure of FEG\angle FEG in triangle EFGEFG?
  2. How can the properties of a parallelogram be used to find other angles in the diagram?
  3. What is the measure of BCF\angle BCF in the parallelogram BCEFBCEF?
  4. How can the exterior angle theorem help solve problems in triangle geometry?
  5. What properties of isosceles triangles are essential in solving angle problems?

Tip: Remember that the sum of angles in a triangle is always 180180^\circ, and this fundamental rule can help solve various geometric problems.

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Math Problem Analysis

Mathematical Concepts

Geometry
Angles in triangles
Properties of parallelograms

Formulas

Sum of angles in a triangle: angle A + angle B + angle C = 180°
Sum of angles on a straight line: angle A + angle B = 180°

Theorems

Isosceles triangle theorem
Exterior angle theorem

Suitable Grade Level

Grades 8-10